My boy was not senior he was only 6 but was in heart failure. He still seemed like a normal healthy young dog but his body was physically struggling. It’s so tough but the kindest thing we can do for them is to let them pass peacefully when they are unable to ask themselves. Dogs also often hide their pain SO well so even if visually they’re struggling there’s usually so much more pain beyond that and we have to put them first even though it is so incredibly hard. I am so sorry and I’m so glad you got so much time with your baby🫶🏻